1. Field of the Invention
The present invention relates to pitot static tubes, and more particularly, to a repairable pitot static tube which may be disassembled to repair or replace component pans.
2. Discussion of the Prior Art
Pitot static tubes are used on aircraft for measuring certain parameters such as air speed. The pitot static tube extends from the body of the aircraft such as from the fuselage or the wing, and measures the difference between pitot pressure and static pressure to provide an indication of the speed of the aircraft. Pitot static tubes usually include a heating element to melt off any ice that may form on the tube or which would clog the flow openings on the tube during flight.
Typically, a pitot static tube has a mounting plate from which a body portion extends at an angle and terminates in a barrel which is generally parallel to the body or wing of the aircraft on which the pitot static tube is mounted. In the past, many pitot static tubes were of unitary construction; that is, the body, mounting bracket and barrel were of single piece construction. In the event that the pitot static tube became damaged, or in the event of a burnout of the heating element, the entire pitot static tube had to be removed and discarded and replaced with an entirely new unit. This led to increased costs, since the entire pitot static tube had to be replaced regardless of whether the cause was due to a major problem or a minor malfunction.
There is known in the prior art several pitot static tubes which are partially repairable, specifically in which the barrel portion of the tube may be disassembled to remove a heating element in the barrel. Pitot static tubes of this type are shown in U.S. Pat. No. 1,971,534 to Peace, Jr., U.S. Pat. No. 2,254,155 to Reichel, and U.S. Pat. No. 2,482,701 to Anderson, and these devices provide access to the heater from one end of the barrel only. Peace, Jr. requires the use of special adapters and contact plates to create the electric circuit to provide power to the heater, while both Reichel and Anderson provide for removal of a coiled heater which requires special handling during insertion into the tube to connect the contact ends of the heating element at the end of the elongated arms of the heater.
Several pitot static tubes also include a heating element in the body portion of the pitot static tube which extends from the mounting plate to the barrel. Typically, this heating element is non-removable, since access to the heating element may only be gained through destruction of the body portion. While some attempts have been made to provide a removable heater in the body portion, such as in U.S. Pat. No. 4,275,603 to Kalocsay, heating elements of this type rely on indirect heating by maintaining contact with the outer body of the pitot static tube. Such a construction may lead to increased damage to the heater since it is positioned adjacent the external surface of the body of the pitot static tube, and further limits the heating capability of the heater since it is typically provided at only one point along the external surface of the body portion and will lose heat to the atmosphere.
The novel repairable pitot static tube of the present invention obviates the disadvantages encountered in the prior art and provides a means for repairing a pitot tube by allowing access to the heating mechanisms positioned inside both the barrel and the body of the pitot static tube. There is also provided a means for extending the length of the barrel as well as provisions for adding additional heaters to the extended barrel. The device of the present invention allows for repair of the pitot tube on-site and permits access to the heater in the barrel portion from either end of the barrel. In addition, the entire assembly is removable from the fuselage or wing of an aircraft so that the heating mechanism in the body portion may be removed for replacement if necessary.